The Blue Lagoon is a must see. We went back there as the time we had didn't do it justice. More info tho about not having sufficient time to get lunch would have been useful as with 2 kids and limited selection at the cafe, we were more interested in getting to the cafe at 4pm rather than the waterfall, as we were starving! Top tip - buy something at the bakery next door to Grays ticket office before you leave - we only realised you could do this once someone had got on board with croissants!!!